Evaporation

Evaporation

3V Tech designs and supplies tailor-made evaporation plants, which
can be arranged as skid-mounted units or suitable systems for on-site
installation.

Some industrial processes require the concentration of a solution, evaporating the solvent.Evaporation plants are widely used for concentration of liquids in the form of solutions, suspensions and emulsions.

Typical applications

Improving quality and/or stability of the final product

Pre-concentration step for final product crystallization or drying

Solute purification from process or waste streams

Solvent recovery from process or waste streams

Volume reduction for lower transport or disposal cost

Evaporator types3V Tech's evaporation systems, operating under vacuum in the most of cases or at atmospheric condition, optimally use and combine the following technologies:

Falling film evaporators FFE

Forced circulation evaporators FCE

Thin/Wiped film evaporators TFE

Short path evaporators SPE

Depending on the application, our evaporators are fabricated with proper alloy or high quality glass-lined.

General guidelines for evaporator selection

Where high capacity is required, usually falling film evaporators FFE bare the first choice

When solids content and fouling tendency prevail, forced circulation evaporators FCE are the best suited

Where the product is difficult to handle due the extreme temperature sensitivity, high viscosity, high boiling point or heavy solids, a technology such as agitated thin/wiped film evaporator TFE is required

Short path evaporators SPE are suitable for special applications under extreme vacuum condition with high boiling products.

Often, a combination of two or more evaporator types is foreseen in multiple-effect or in pre-concentrator plus a high concentrator system

Energy saving & plant arrangementTo evaporate 1 kg of solvent, an amount of energy corresponding to the latent heat of the same must be provided, plus sensible heat for pre-heating, heat losses, etc. In case of water evaporation, a single-effect evaporator heated by direct steam thus presents a specific consumption of approx. 1,05 to 1,25 kg of steam per kg of evaporated water.According to the requirements, 3V TECH designs the optimal energetic arrangement of the evaporation plant, in order to minimize capital and operating cost. Some of the options we apply:

Multiple effect arrangement (ME)

Thermal vapor recompression (TVR)

Mechanical vapor recompression (MVR)

Use of waste heat (e.g. waste steam, hot water, etc.)

Combination of several techniques

Multiple effect arrangement (ME)

Direct heating by live steam, thermal oil, waste heat

The heating medium in any subsequent effect is the vapor generated in the previous calandria, which condensates at lower pressure. Vapor from the final effect is condensed by cooling water

The arrangement can be co-current flow or counter flow or only partially in counter flow, depending on the application

The number of effects is limited by thermal product degradation, material corrosion and boiling point elevation (BPE) of the concentrate solution

In case of water evaporation, the specific steam consumption in 3V Tech systems is typically 1,05 to 1,25 kg of live steam per kg of evaporated water, divided by the number of effects

Thermal vapor recompression (TVR)

The heating medium is part of the process vapor, recompressed to a higher temperature level together with motive steam by means of a steam ejector, according to the principle of jet pump

No-recompressed part of process vapor is condensed in a further effect or in a condenser at lower pressure

The higher the compression ratio of delivery pressure vs. suction pressure (e.g. in case of high BPE), the higher will be the specific motive steam consumption

The lower the motive ratio of motive steam pressure vs. suction pressure (e.g. in case of low pressure steam available), the higher will be the specific motive steam consumption

Steam ejectors have no moving parts, construction is simple and operation reliable

Depending upon the operating conditions, the thermal vapor recompressor can act as several additional effects

In case of water evaporation with the ejector installed across the first stage of a ME system, the specific steam consumption in 3V Tech systems is typically 1,05 to 1,5 kg of live steam per kg of evaporated water, divided by the (number of effects+1)

Mechanical vapor recompression (MVR)

The heating medium is the total amount of the process vapor, recompressed to a higher temperature level by means of a mechanical compressor, according to the principle of heat pump

Live steam consumption is very low, just for start-up and make-up, being electric energy (the energy input to the plant) used instead of steam

The boiling point elevation (BPE) increases the pressure ratio that the compressor must attain to effect vaporization. The higher the compression ratio of delivery pressure vs. suction pressure (e.g. in case of high BPE), the higher will be the specific electric energy consumption

Due the complete recompression of the process vapor, another advantage of the MVR systems is the negligible consumption of cooling water